After 20 years of decline, the number of these beauties is finally recovering. The amount of monarch butterflies staying in Mexico this winter went up dramatically, increasing in area by 255 percent over last year.

Populations of monarchs are measured in acres due to their migration patterns. In Eastern North America, monarchs spread across the United States and Canada in the warmer months, but migrate back to Mexico as winter approaches, clustering back into a small section of forest. Their populations coat the trees and branches so thoroughly that researchers measure the area of land covered instead of trying to count individual butterflies.

This year, the area covered measures almost 10 acres, which is a lot more than the 2,8 acres from last year

That’s optimistic news for researchers hoping to see the population once again meet its 1996 peak of 44.5 acres. The monarch population hit its low in the winter of 2013 and 2014 when the area covered by butterflies was a slender 1.6 acres.

“We are seeing the beginning of success,” Daniel Ashe, director of the United States Fish and Wildlife Service, told the New York Times. “Our task now is to continue building on that success.”

Monarch butterflies continue to face threats, mostly a decline in habitat in Mexico due to illegal logging, and a loss of their preferred food, milkweed, along their route through North America. They actually will need to find milkweed plants, which is the only plant they can lay their eggs on because that’s the only plant the caterpillars can feed on.

Thankfully, there are new programs in place to establish milkweed planting, and the public is very much urged to do so.